Abstract
An attempt was made to know whether the late phase block of nicotine on the superior cervical ganglion is due to the same mechanism of action as that of the competitive blocking agents by a quantitative comparing method.
From the evaluation of the total blocking value, it was found that the combination effect of nicotine with TEA or C6 was strongly potentiated while the combination effect of TEA and C6 was less than the addition of their values. It has been shown that nicotine did not affect the contraction responses to muscarinic substances injected to the superior cervical ganglion. These facts may indicate that the sites of action of nicotine at the late phase block are both the receptor site of the ganglion cell and the preganglionic terminals.
